Breakthrough: We can now know the color of long-extinct mammals from fossils alone

Detective work 300 million years later

Figuring out what an extinct species looked like based on just fossils requires a lot of guesswork and artistic license, especially when big pieces of the puzzle were lost in time. A good example is the mid-1990s discovery of fossilized dinosaur feathers, changing our whole perception of the Jurassic Park creatures (though some people will forever cling to their childhood image of more lizard-like dinos).

Another tough problem: Until recently, figuring out what color an animal was based on just a fossilized skeleton was impossible. But thanks to scientists at Virginia Tech and the University of Bristol, we can now analyze melanin preserved in fossils to reveal the original color of species that lived millions of years before humans arrived on the scene.

The techniques described in the Proceedings of the National Academy of Sciences can be used to determine color from well-preserved animal fossils that are up to 300 million years old, the researchers said.

“We have now studied the tissues from fish, frogs, and tadpoles, hair from mammals, feathers from birds, and ink from octopus and squids,” said Caitlin Colleary, a doctoral student of geosciences in the College of Science at Virginia Tech and lead author of the study. “They all preserve melanin, so it’s safe to say that melanin is really all over the place in the fossil record. Now we can confidently fill in some of the original color patterns of these ancient animals.”

This is possible because some structures that were previously thought to be fossilized bacteria turn out to be melanosomes, the organelles within cells that contain melanin, the pigment that gives colors to hair, feathers, skin, and eyes.

“Very importantly, we see that the different melanins are found in organelles of different shapes: reddish melanosomes are shaped like little meatballs, while black melanosomes are shaped like little sausages and we can see that this trend is also present in the fossils,” said Jakob Vinther, a molecular paleobiologist at the University of Bristol. “This means that this correlation of melanin color to shape is an ancient invention, which we can use to easily tell color from fossils by simply looking at the melanosomes shape.”